Hydraulic circuits of conventional brake systems allow an operator to halt a moving machine. However, the hydraulic circuits are designed in a manner that a full braking force may be implemented rapidly on the wheels of the machine in order to halt the machine. During emergency conditions or failure of any component in the hydraulic circuit or an electrical system associated with the brake system, the sudden braking imposed on the wheels of the machine may sometimes cause the machine to skid and loss of control.
Further, the hydraulic circuits may use several single-chambered valves to effect braking on the wheel. When an emergency condition arises due to a failure of any component of the hydraulic or electric system associated with the brake system, the numerous valves may entail individual modulation and may cause a delay in application of brakes. Furthermore, the brakes may need to be applied in a gradual manner to avoid skidding of the wheels on the ground surface. Therefore, the conventional hydraulic circuits may not be effective in operation and may not gradually halt the machine in an event of a failure.
U.S. Published application Ser. No. 13/049,335 relates to a method for operating a parking brake module that is at least partially integrated into a compressed air generation system in the event of defects, having a control unit, solenoid valves, and a relay valve for aerating and deaerating at least one spring-loaded brake cylinder. A pressure in the parking brake module which is elevated compared to a normal pressure is determined. A constant compressed air delivery is stopped. A reduced switch-off pressure of the compressed air generation system is set. The pressure level in the parking brake module is lowered to the reduced switch-off pressure through repeated activation of the relay valve.